Axial Deformation Detection Research Of Rectangular Rubber Sealing Ring Based On Tightening Torque

With the rapid development of automation technology and the continuous improvement of the level of assembly,solid rocket motor tightening assembly by the traditional manual method is also gradually replaced by automated assembly. The main technical index of solid rocket motor tightening assembly is to ensure the air tightness of the device, and the rectangular rubber sealing ring is the only seal in the solid rocket motor, its size of the axial deformation has a direct influence on the air tightness of the device. However, due to the influence of the structure and assembly process of the solid rocket motor, it is difficult to directly measure the axial deformation of rectangular rubber sealing ring in the process of tightening that makes it difficult to realize the effective control of the axial deformation of the rectangular ring by existing automatic tightening control system, so it will seriously affect the reliability of the automatic assembly of solid rocket motor. Therefore, this paper studies the problem of detection of the axial deformation of the rectangular rubber sealing ring in tightening process based on the a Research Institute's solid rocket motor automatic tightening assembly project.This paper began with the process and structure characteristics of the solid rocket motor, then the mechanism of tightening process was analyzed, and the composition of tightening torque and its influencing factors were defined. On the basis of this, the relationship between the tightening torque and the axial deformation of the rectangular rubber sealing ring was studied. Thus, the detection model of the axial deformation of the rectangular rubber seal ring based on tightening torque was established.In the process of establishing the detection model, for the structural features of the thread interface of solid rocket motor, combined with elastic mechanics and differential principle, we analyzed the mechanical behavior of the thread interface, and established the numerical model of the relationship between the thread friction torque and the axial stress of the rectangular ring. For the material properties of the rectangular rubber sealing ring and used the Mooney-Rivlin strain energy function model and rectangular micro element theory, the stress and strain characteristics of rectangular rubber ring within the small deformation interval was analyzed in the process of fastening assembly, and established the numerical model of the relationship between the rectangular ring friction torque and the axial deformation of the rectangular ring. At the same time, for the established numerical model, used ABAQUS finite element analysis software to establish the two-dimensional axisymmetric model of assembly process. Then the numerical model was simulated and verified, which lays the foundation for the establishment of the detection model. For the problem that the rectangular rubber ring axial deformation is difficult to detect during solid rocket motor tightening, combined with tightening torque constitution, based on the established numerical model, the numerical model of the relationship between the tightening torque and the axial deformation of the rectangular rubber sealing ring was established. Finally, the verification test was designed based on the solid rocket motor automatic tightening device, the experimental results show that the numerical model of the relationship between the tightening torque and the axial deformation of the rectangular rubber sealing ring can better reflect the influence of the axial deformation of the rectangular ring on the tightening torque during the tightening, and can provide appropriate theoretical basis and model reference for the automatic assembly of solid rocket motor.